Scrollview stuttering problem on content inset/offset change fixed

Hi, first of all thanks for the great work! :)

However I had a problem, possibly with auto-layouted scrollviews - they jumps up during KB show/hide animations.
In the project's sample I not found this issue, so I think it can be associated with the autolayouted views.
But if you wanna see some achievement from this commit quickly, the sample's collection view top part also healed (currently you can see a disappearing gray box during KB animation).

Cheers